1) On September 21, 1888, the Connecticut State Agricultural Experiment Station opened in New Haven, becoming the first agricultural experiment station in the United States. The station's mission was to research and develop new farming techniques to improve crop yields and soil health.

2) In 1780, Major General Benedict Arnold, who had defected to the British side during the Revolutionary War, led a raid on New London, Connecticut. The attack left the town in ruins and led to the deaths of many American soldiers and civilians.

3) On September 21, 1938, the "Great New England Hurricane" made landfall in Connecticut, causing widespread destruction and claiming over 600 lives across the region. It remains one of the deadliest and most destructive hurricanes in New England history.

4) In 1863, the Battle of Chickamauga ended in Georgia, with Connecticut soldiers playing a significant role in the Union victory. This battle was one of the bloodiest of the Civil War, with over 34,000 casualties on both sides.

5) On September 21, 1970, the first Earth Day was celebrated in Connecticut, with events taking place at various locations across the state. This event helped raise awareness about environmental issues and sparked a movement that continues to this day.